1. Field
The present disclosure relates generally to communications, and more particularly, to wireless handoffs between multiple wireless networks.
2. Background
The demand for mobile access to information has led to the development of an ever increasing number of wireless networks. Associated with each wireless network is a wireless communications standard that allows two wireless devices that support the standard to freely communicate over the network. CDMA2000 1x is just one example of a wireless communications standard that provides wide area telephony and data services. Promulgated by the Third Generation Partnership Project 2 (3GPP2), CDMA2000 1x is a wireless communications standard based on Code Division Multiple Access (CDMA) technology. CDMA is a technology that allows multiple users to share a common communications medium using spread-spectrum processing.
In addition to CDMA2000 1x, many other wireless communication standards exist today. By way of example, CDMA2000 1xEV-DO is a wireless communications standard optimized for data transmission using CDMA technology. Global System for Mobile Communications (GSM) is another wireless communications standard which is commonly employed in Europe. Unlike CDMA2000 1x and CDMA 1xEV-DO, GSM uses narrowband Time Division Multiple Access (TDMA) to support wireless telephony and data services. Enhanced Data for GSM Evolution (EDGE) is a further development of the GSM protocol designed to handle high speed data transmission. Some other wireless communication standards include General Packet Radio Service (GPRS) which supports high speed data services with data rates suitable for e-mail and web browsing applications and Universal Mobile Communications System (UMTS) which can deliver broadband voice and data for audio and video applications.
These wireless communication standards are generally used over cellular networks. The term “cellular network” is intended to cover any wireless network in which the service area is broken up into cellular regions, without regard to the type of service provided. Thus, a cellular network as used herein would includes any cellular topology that provides cellular services, Personal Communications Services (PCS), or any other type of services. Moreover, the cellular network may be based on any suitable wireless communications standard incorporating one or more multiple access technologies, including by way of example, CDMA, Wideband CDMA (WCDMA), Direct Sequence CDMA (DS-CDMA), TDMA, Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or the like.
As the demand for wireless access to information continues to increase, wireless communication devices are evolving to support integrated voice, data, and streaming media while providing seamless network coverage between cellular and Internet-Protocol (IP) networks. These IP networks may be accessed by a wireless device through one or more access points (APs) residing in a wireless Local Area Network (LAN). Typically, multiple wireless LANs will be distributed throughout the cellular network. These LANs may use any suitable wireless data networking protocol, including by way of example, WiFi, WiMax, Bluetooth, HomeRF, Ultra-WideBand (UWB), or the like.
The existence of wireless LANs in cellular networks provides a unique opportunity to increase user capacity by extending cellular communications to the infrastructure of the IP network. Under certain circumstances, cost savings may be realized by routing communications over the IP network. However, the commercial viability of this approach depends largely on the ability to maintain active calls across these networks.